Re: Array_agg and dimensions in Array

Hi Mike,
> I have come across a problem which I cant seem to solve in a nice way
> Basically I have a (small) table of tags
> What I need to is combine two concatenated fields with a literal value
> as an array element.
You can create a custom aggregate function like this:

alexey(at)[local]/alexey=# create aggregate array_cat_agg(anyarray) (SFUNC
= array_cat, STYPE = anyarray, COMBINEFUNC = array_cat, PARALLEL = SAFE);
CREATE AGGREGATE

And use it like this:

alexey(at)[local]/alexey=# select grp, array_cat_agg(array['--foo', bar ||
'=' || baz]) from (values ('g1', 'a', 'b'), ('g1', 'c', 'd'), ('g2',
'e', 'f')) _ (grp, bar, baz) group by grp;
┌─────┬───────────────────────┐
│ grp │     array_cat_agg     │
├─────┼───────────────────────┤
│ g2  │ {--foo,e=f}           │
│ g1  │ {--foo,a=b,--foo,c=d} │
└─────┴───────────────────────┘
(2 rows)

Is that what you need?

Best, Alex